"The methodology that the CDC uses to define liver-related mortality is somewhat limited," says W. Ray Kim, M.D., (http://www.mayoclinic.org/bio/11801271.html) a gastroenterologist with Mayo Clinic. "They only look at a certain diagnostic code, and deaths due to other facets of liver disease are not included.

"There are a large number of people with hepatitis C in the U.S. They are getting older and experiencing complications. Also, associated with the 'obesity epidemic,' a large number of individuals have fatty liver disease. Some go on to develop end-stage liver disease, cirrhosis, or liver cancer. In order to discover the true impact of liver disease on the population, we analyzed mortality data using these more comprehensive criteria."

The research team examined data from the CDC's national death registry for deaths among adults during 1979-2006 and compared their results to statistics from the Rochester Epidemiology Project, (http://www.mayoresearch.mayo.edu/rep/) a long-term, collaborative medical records project among health care providers in Olmsted County, Minn.

"We had a good correlation between the national statistics and the Olmsted County mortality data," says Dr. Kim. "Of course, the most common cause of death for adults is cardiovascular disease and cancer. However, we found that liver disease is not far behind in terms of being No. 4 for people between the ages of 45 and 64 years."

Dr. Kim says that obese people and those with hepatitis C need to be watched especially closely for liver disease as part of their overall medical management program. "Liver disease is an important cause of morbidity and mortality in the U.S. -- more than we have recognized in the past -- and as physicians, we need to be aware of that," he says.